A 35-year-old man was arrested Friday night for the murder of a policeman, according to Orleans Parish jail records and the NOPD.

John Shallerhorn was booked early Saturday morning for armed robbery and 1st degree murder of a policeman.

The New Orleans Police Department says Tulane Police Officer Martinus Mitchum was shot while providing security for a basketball game at George Washington Carver High School in the 3000 block of Higgins Boulevard.

The NOPD says Shallerhorn arrived at the school and was refused entry due to not having on a mask.

A physical altercation ensued with a school employee. The Tulane Officer intervened and escorted the suspect out.

As Shallerhorn was leaving, he shot the officer twice, then placed the weapon on the ground and was taken into custody.

NOPD Superintendent Shaun Ferguson says the officer, who has not been identified, was also a reserve officer for the 2nd City Court Constable.

Tulane Police Chief Kirk Bouyelas issued a statement Saturday morning saying, 'we are deeply saddened by the senseless and tragic death of TUPD Corporal Martinus Mitchum. Corporal Mitchum was a dedicated police professional who had a heart of service for the Tulane community. We have reached out to his family and are providing support to his fellow officers during this difficult time. Our thoughts and prayers are with his family and with all the fellow officers with whom he served.'

Just moments before Shallerhorn attempted to enter the school, he robbed a man at gunpoint in the parking lot. Police say a 39-year-old man was sitting inside his vehicle when he was approached by the suspect.

Shallerhorn raised his shirt and brandished a gun while demanding the victim's medallion chain. The victim complied.

Shallerhorn has a prior arrest in August of 2019 for indecent behavior with a juvenile, arrest records show.

The Orleans Parish District Attorney's Office refused that charge in November 2019.